Thin film capacitors for core and adjacent build up layers

ABSTRACT

A method includes affixing a capacitor sheet adjacent to core material of a device substrate, where the capacitor sheet covers a surface of the core material. The method also includes patterning first openings through both capacitor sheet and the core material, where the first openings are larger than a substrate pass through-hole. The method additionally includes filling the first openings with an electrically inert material. The method further includes patterning a second openings parallel to the first openings through the electrically inert material, where the second openings are at least as large as the substrate pass through-hole and having sidewalls enclosed within the electrically inert material.

BACKGROUND

The present disclosure relates to electrical device substrates, and morespecifically, to integrating thin film capacitor sheets adjacent to, andin place of, the core material of device substrates with substrate passthrough-holes.

A substrate in the field of electronic device manufacturing andpackaging is a substance on which one or more layers of anothersubstance is deposited. The substrate can serve as a foundation forelectronic circuits (e.g., a semiconductor device or chip), includingactive and passive electrical components. Pass through-holes can be cutin a substrate to electrically connect signals one surface of asubstrate to signals on another surface of the substrate.

SUMMARY

According to embodiments of the present disclosure, a method includesaffixing a capacitor sheet adjacent to core material of a devicesubstrate, where the capacitor sheet covers a surface of the corematerial. The method also includes patterning first openings throughboth capacitor sheet and the core material, where the first openings arelarger than a substrate pass through-hole. The method additionallyincludes filling the first openings with an electrically inert material.The method further includes patterning a second openings parallel to thefirst openings through the electrically inert material, where the secondopenings are at least as large as the substrate pass through-hole andhaving sidewalls enclosed within the electrically inert material.

According to various embodiments, a method for creating a devicesubstrate includes generating a core structure of the device substrate,where the core structure comprising a capacitor sheet. The method thenincludes patterning a first openings through the core structure, wherethe first openings are larger than a substrate pass through-hole. Themethod further includes filling the first openings with an electricallyinert material. The method further includes patterning a second openingsthrough the electrically inert material, where the second openings areat least as large as the substrate pass through-hole and havingsidewalls enclosed within the electrically inert material. The methodadditionally includes depositing one or more material layers on at leastone surface of the core structure.

According to various embodiments, a device substrate includes a corematerial. A capacitor sheet can be affixed adjacent to a surface of thecore material, where the capacitor sheet covers the surface of the corematerial. A first opening can extend through both capacitor sheet andthe core material, where the first opening are larger than a substratepass through-hole. An electrically inert material can fill the firstopening. A second opening extending parallel to the first openingthrough the electrically inert material, where the second opening is atleast as large as the substrate pass through-hole and having sidewallsenclosed within the electrically inert material.

The above summary is not intended to describe each illustratedembodiment or every implementation of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings included in the present application are incorporated into,and form part of, the specification. They illustrate embodiments of thepresent disclosure and, along with the description, serve to explain theprinciples of the disclosure. The drawings are only illustrative ofcertain embodiments and do not limit the disclosure.

FIG. 1 depicts a set of operations for integrating thin film capacitorsheets adjacent to the core material of a device substrate, according tovarious embodiments.

FIG. 2 depicts a set of operations for creating a device substratehaving sheets of thin film capacitors as the core material, according tovarious embodiments.

FIG. 3 depicts a block diagram of a sectioned perspective view of adevice substrate integrating thin film capacitor sheets adjacent to thecore material of a device substrate, according to various embodiments.

FIG. 4 depicts a block diagram of a cross-sectional view a devicesubstrate integrating thin film capacitor sheets adjacent to the corematerial of a device substrate, according to various embodiments.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

Aspects of the present disclosure relate to electrical devicesubstrates, more particular aspects relate to integrating thin filmcapacitor sheets adjacent to, and in place of, the core material ofdevice substrates with substrate pass through-holes. While the presentdisclosure is not necessarily limited to such applications, variousaspects of the disclosure may be appreciated through a discussion ofvarious examples using this context.

Functionality of an electrical device substrate (hereinafter,“substrate”) can be degraded or limited due to, for example, noise(e.g., high frequency noise) and parasitic circuit characteristics(e.g., inductance). Capacitors can be added to a substrate, or to anelectrical device package, to filter noise. These capacitors can alsodecouple different devices or circuits supported by a substrate to limitor attenuate the effect of some parasitic circuit characteristics.Adding capacitors (e.g., decoupling or bypass capacitors) to asubstrate, or to a device module, to address these concerns can consumemodule area, decreasing available area for input/output (I/O) circuitryand limiting the number of pass through-holes supported by thesubstrate. Some designs can address this problem by embedding discretecapacitors in the laminate of a substrate. This solution can, however,limit the number of pass through-holes in a design. Embedded discretecapacitors can also be sensitive to mechanical degradation due tolocalized stress and the environment surrounding the discretecapacitors.

Embodiments of this disclosure are based on the recognition that asubstrate constructed with sheets of thin film capacitors affixedadjacent to a substrate core, or use instead of a substrate core, andmodified to have pass through-holes formed through both the sheets ofthin film capacitors and the substrate core, can improve the performanceof electronic devices constructed using these substrates. A thin filmcapacitor sheet can be less susceptible to mechanical stress thanembedded discrete capacitors due, at least in part, to the stressesbeing distributed along the area of the thin film capacitor sheet.Additionally, because pass through-holes are formed, or patterned,through the thin film capacitors sheets and the adjacent substrate core,this solution can be implemented without having to reduce the number ofpass through-holes in a design.

As used herein, the terms coupled to, affixed to, and disposed on, referto a physical connection between a first layer of material and a secondlayer of material. One or more intervening layers of materials (e.g.,adhesive materials) be used to physically connect the first layer to thesecond layer.

As used herein, the terms above, adjacent to, below, and on refer to aposition of a first layer of material relative to a second layer ofmaterial. In some embodiments, adjacent to can refer to a relativeposition between a first layer and a second layer, where minimum numberof intervening layers separate the first layer and the second layer. Aminimum number of intervening layers can, for example, be layers ofmaterial (e.g., an adhesive layer) required to affix or connect thefirst layer to the second layer.

As used herein, an opening can be a void, a cavity, a hole, or a bore.An opening in a material extends through at least two surfaces of thematerial.

As used herein, the term substrate refers to a solid material, orsubstance, onto which electrical devices (e.g., semiconductor chips),electrical circuits, passive and active electrical components, and oneor more layers of other materials can be affixed. The term substrate caninclude a device substrate, packaging substrate, and printed circuitboard substrates. A substrate can include a core material, or a corematerial of a substrate, composed of one or more layers on which othersubstrate layers are build. The core material can add structural supportto a substrate, and can include material such a fire retardant glassfiber epoxy laminate.

According to various embodiments, a substrate can be constructed byaffixing a capacitor sheet (e.g., a thin film capacitor sheet) adjacentto a core material of the substrate. Openings (e.g., first openings) canbe patterned (e.g., drilled or cut) through both the capacitor sheet andthe core material. The patterned openings can be larger than openings ofpass though-holes specified, or selected, for the substrate. Theopenings can be filled with an electrically inert material (e.g., aresin). The electrically inert material can harden or solidify withinthe openings. A second set of openings can then be patterned though thehardened electrically inert material. The second set of openings can beparallel to the first openings and can extend through the electricallyinert material. Additionally, the second set of openings can be at leastas large as pass through-holes selected for the substrate, but smallerthat the first set of openings to ensure that the sidewalls of eachopening in the second set of openings is enclosed within, or surroundedby, the electrically inert material.

In some embodiments, the capacitor sheet can be a laminate having atleast a conductive layer and a dielectric layer. The laminate caninclude several layers of conductive and dielectric material. Theadditional layers can improve the structural stability of the laminate,as well as enable larger capacitance values. In certain embodiments, thecapacitor sheet can be patterned, prior to being affixed adjacent to thecore material to form two or more capacitor sheets. The two or morecapacitor sheets can be electrically isolated from each other. Each ofthe two or more capacitor sheets can then be affixed adjacent to thecore material as electrically isolated capacitors.

In some embodiments, patterning the second set of opening can includedrilling the openings with a drill. Patterning the second set ofopenings can further include cutting the openings with a laser.

The second set of openings can be pass through-holes, or resin filledpass through-holes, incorporated in the substrate and in the capacitorsheets. Electrical conductors, or electrically conductive material, canbe deposited in the second set of openings as, for example, part of thesubstrate build up process.

According to various embodiments, a device substrate can be constructed,or created, by generating a core structure of the device substrate. Thecore structure can be a capacitor sheet (e.g., a thin film capacitorsheet or laminate). The capacitor sheet can include two or morealternating layers of conductive and dielectric material. Openings(e.g., first openings) can be patterned through the core structure. Thepatterned openings can be larger than openings of pass though-holesspecified, or selected, for the substrate. The openings can be filledwith an electrically inert material. The electrically inert material canharden or solidify within the openings. A second set of openings canthen patterned though the hardened electrically inert material. Thesecond set of openings can be parallel to the first openings and canextend through the electrically inert material. Additionally, the secondset of openings can be at least as large as pass through-holes selectedfor the device substrate, but smaller that the first set of openings toensure that the sidewalls of each opening in the second set of openingsis enclosed within, or surrounded by, the electrically inert material.The device substrate can be further built up by depositing, adding, oraffixing, one or more material layers to at least one surface of thecore structure.

According to various embodiments, electrical conductors, or electricallyconductive material, can be deposited in the second set of openings as,for example, part of the substrate build up process. In certainembodiments, openings can be made in at least one of the one or morematerial layers, and electrical conductors can be deposited within theseopenings as well as in the second set of openings.

According to various embodiments, a device substrate can include a corematerial with a capacitor sheet affixed adjacent to a surface of thecore material. The capacitor sheet can cover, or substantially cover(e.g., cover a majority of), the surface of the core material. A set ofopenings (e.g., first openings) can extend through both the capacitorsheet and the core material. The set of openings can be larger thansubstrate pass through-holes selected for the device substrate. The setof openings can be filed with an electrically inter material. Theelectrically inert material can have a second set of openings extendingparallel to the first openings through the electrically inert material.Additionally, the second set of openings can be at least as large aspass through-holes selected for the substrate, but smaller that thefirst set of openings to ensure that the sidewalls of each opening inthe second set of openings is enclosed within, or surrounded by, theelectrically inert material.

Referring now to the figures, FIG. 1 depicts a set of operations 100 forintegrating thin film capacitor sheets adjacent to the core material ofa device substrate, according to various embodiments. The operations 100can be executed, performed, or carried out, as a part of a substratebuild up process. As preliminary step, as substrate core can begenerated, or prepared according to know substrate build up techniques.The operations 100 can be then be executed before additional layers orcomponents are added to the substrate core.

At operation 105, a capacitor sheet can be affixed adjacent to the corematerial of a device substrate. The capacitor sheet can be a thin filmcapacitor laminate composed of at least a layer of conductive materialand a layer of dielectric material. Examples of conductive materialsinclude copper and nickel foils. Examples of dielectric materialsinclude materials that have a high dielectric constant, such as bariumtitanate. In embodiments, the capacitor sheet can be a laminate composedof a layer of barium titanate disposed between a layer of copper foiland a layer of nickel foil. Some capacitor sheets can include two ormore alternating conductor and dielectric layers. Other capacitor sheetscan include two or more alternating insulator and dielectric layerscollectively disposed between conductor layers. Capacitor sheets cantypically be on the order of 30-200 micrometers thick. In certainembodiments, the capacitor sheet can have a capacitance on the order of1-5 microfarads per square centimeter. A capacitor sheet affixed to acore material of a device substrate can have capacitance values on theorder of 20 microfarads.

Affixing a capacitor sheet to a core material of a substrate can includedepositing an adhesive coating or layer (e.g., adhesive copper) to asurface of the core material. A capacitor sheet (e.g., a laminate)patterned to over an area of the core material (e.g., the entiresurface, or a majority of the entire surface) can then be disposed overthe adhesive material.

In some embodiments, prior to affixing a copper sheet to a core materialof a substrate, the copper sheet can be patterned to generate two ormore electrically isolated copper sheets. The patterning can includecutting the copper sheet along one dimension of the sheet to generatetwo or more smaller sheets. Each of the two or more smaller sheets canthen be affixed to the substrate core. Each of the two or more sheetscan thus form capacitors that couple to two or more voltage domains.

At operation 110, openings (e.g., first openings) can be patternedthrough both the capacitor sheet and the core material. The openings(e.g., a diameter of the openings) can be larger than substrate passthrough-holes selected, or specified, for the substrate. Patterning theopenings can include drilling using a drill bit that creates holeslarger than a pass through-hole selected for the substrate (e.g., atraditional pass through-hole). Patterning the openings can also includeusing a laser to cut holes larger than a pass through-hole selected forthe substrate.

At operation 115, the openings can be filled with an electrically inertmaterial. The electrically inert material can be a material that isinitially fluidic, but later hardens, either on its own or after beingcured. Filling the openings can include curing the inert material tocause it to solidify. Examples of an electrically inert material includeresins, such as glass-epoxy materials.

At operation 120, openings (e.g., second openings) can be patternedthrough the electrically inert material. These second openings can be atleast as large as substrate pass through-holes selected for thesubstrate, but smaller that the first set of openings to ensure that thesidewalls of each opening in the second set of openings is enclosedwithin, or surrounded by, the electrically inert material. In someembodiments, the second openings are substrate pass through-holeopenings. In these embodiments, pass through-hole conductors can bedeposited in the second openings subsequent to the drilling. The secondopenings can be patterned by drilling, using a drill, or by cutting,using a laser, as described herein.

Standard substrate processing techniques can further be used to drill orpatter holes in the capacitor sheets to make electrical connections topower and ground legs.

FIG. 2 depicts a set of operations 200 for creating a device substratehaving sheets of thin film capacitors as the core material, according tovarious embodiments. The operations 200 can be executed, performed, orcarried out, as a part of a substrate build up process.

At operation 205, a core structure of the device substrate can begenerated. The core structure can be composed of a capacitor sheet, orlaminate, having at least a conductive layer and a dielectric layer. Insome embodiments, the capacitor sheet can include two or morealternating conductor and dielectric layers, or two or more alternatinginsulator and dielectric layers collectively disposed between conductorlayers. The additional layers can enable the capacitor sheet to haveincreased capacitance, as well as to provide structural support for thedevice substrate.

At operation 210, openings (e.g., first openings) can be patternedthrough the core structure. The openings can be larger than substratepass through-holes selected, or specified, for the substrate. Accordingto various embodiments, the openings can be patterned using a drill orlaser, as described herein.

At operation 215, the openings can be filled with an electrically inertmaterial, as described herein.

At operation 220, openings (e.g., second openings) can be patternedthrough the electrically inert material. The second set openings can beparallel to the first openings and can extend through the electricallyinert material. Additionally, the second openings can be at least aslarge as pass through-holes selected for the device substrate, butsmaller that the first openings to ensure that the sidewalls of thesecond openings are enclosed within, or surrounded by, the electricallyinert material.

At operation 225, the device substrate can be further built up bydepositing, adding or affixing one or more material layers to at leastone surface of the core structure.

FIG. 3 depicts a block diagram of a sectioned perspective view of adevice substrate 300 integrating thin film capacitor sheets 325 and 330adjacent to core material 350, according to various embodiments.

Capacitor sheets 325 and 330 are a laminates having conductive layers335 and 345, and dielectric layer 340. While the capacitor sheets 325and 330 are depicted as having only three layers, the capacitor sheetscan include two or more layers of alternating conductor, insulator, anddielectric materials, as described herein. In some embodiments theconductive layer 345 is an adhesive layer. According to variousembodiments, the capacitor sheets 325 and 330 can be affixed to corematerial 350 as a single laminate. In certain embodiments, the capacitorsheets 325 and 330 can be patterned to cover a specific area of thesubstrate core 350, and to have a specific electrical characteristics(e.g., capacitance) prior to being affixed to the substrate core 350.

In some embodiments, the capacitor sheet 325, and the capacitor sheet330, can include patterning 385. Patterning 385 can be a pre-patternedseparation, or gap, dividing capacitor sheet 325 into a first capacitorsheet (e.g., the capacitor sheet having substrate pass through-holes 305and 360) and a second capacitor sheet (e.g., the capacitor sheet havingsubstrate pass through-holes 310 and 320).

The capacitor sheets 325 and 330 can be affixed to the core material 350on, or over, the core material surface 375 and 380, respectively. Inother embodiments, the substrate core 350 can be absent, and thecapacitor sheets 325 and 330 can serve as a core structure of the devicesubstrate 300.

The capacitor sheets 325 and 330 can include pass through-holes 305,310, 320 and 360 extending through the capacitor sheets. Each of thepass through-holes 305, 310, 320 and 360 can be created, at least inpart, by opening 355 (e.g., first opening) in the capacitor sheet 325and 330, inert electrical material 365 filling the opening, and secondopening 320 through the inert electrical material. Each of the passthrough-holes 305, 310, 320 and 360 can additionally have sidewalls 370surrounded by, or enclosed within, inert electrical material 365.

FIG. 4 depicts a block diagram of a cross-sectional view an electronicdevice 400 using a substrate integrating thin film capacitor sheetsadjacent to the core material of a device substrate, according tovarious embodiments. The electronic device 400 includes substrate 475,semiconductor device 405 (e.g., a processor, logic circuit, amplifier,etc.) having metal insulator metal capacitors 410 and connected tosolder mask 425 by controlled collapse chip connection 415. Theelectronic device 400 further includes top surface metallurgy capacitors420. The substrate 475 includes build up layers 430 and 450. Thesubstrate 475 further includes substrate core material 440 with affixedcapacitor sheets 435 and 445. The substrate 475 further includes passthrough holes 455 extending through the core material 440 and throughthe capacitor sheets 435 and 445. Land grid array pins 465 couple landgrid array pads 460 to socket 470.

The descriptions of the various embodiments of the present disclosurehave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

1. A method comprising: affixing a capacitor sheet adjacent to corematerial of a device substrate, the capacitor sheet covering a surfaceof the core material; patterning first openings through both capacitorsheet and the core material, the first openings being larger than asubstrate pass through-hole; filling the first openings with anelectrically inert material; and patterning a second openings parallelto the first openings through the electrically inert material, thesecond openings being at least as large as the substrate passthrough-hole and having sidewalls enclosed within the electrically inertmaterial.
 2. The method of claim 1, wherein capacitor sheet is alaminate comprising at least a conductive layer and a dielectric layer.3. The method of claim 1, wherein, prior to the affixing, the capacitorsheet is patterned to form two or more capacitor sheets, and theaffixing comprises affixing each of the two or more sheets adjacent tothe core material.
 4. The method of claim 1, wherein the electricallyinert material is a resin.
 5. The method of claim 1, wherein the secondopenings are a pass though-holes.
 6. The method of claim 1, furthercomprising depositing pass through-hole conductors in the secondopenings.
 7. The method of claim 1, wherein the capacitor sheet is athin film a capacitor sheet.
 8. The method of claim 1, wherein thepatterning includes at least one of drilling using a drill, and cuttingusing a laser.
 9. A method for creating a device substrate, the methodcomprising: generating a core structure of the device substrate, thecore structure comprising a capacitor sheet; patterning a first openingsthrough the core structure, the first openings being larger than asubstrate pass through-hole; filling the first openings with anelectrically inert material; patterning a second openings through theelectrically inert material, the second openings being at least as largeas the substrate pass through-hole and having sidewalls enclosed withinthe electrically inert material; and depositing one or more materiallayers on at least one surface of the core structure.
 10. The method ofclaim 9, further comprising, depositing a through-hole conductor throughthe second openings.
 11. The method of claim 9, wherein capacitor sheetis a laminate comprising at least a conductive layer and a dielectriclayer.
 12. The method of claim 9, wherein the capacitor sheet ispatterned to form two or more sheets, and the affixing comprisesaffixing each of the two or more sheets adjacent to the core material.13. The method of claim 9, wherein the electrically inert material is aresin.
 14. The method of claim 9, wherein the second openings are a passthrough-holes.
 15. The method of claim 9, wherein the patterningincludes at least one of drilling using a drill, and cutting using alaser.
 16. A device substrate, comprising: a core material; a capacitorsheet affixed adjacent to a surface of the core material, the capacitorsheet covering the surface of the core material; a first openingextending through both capacitor sheet and the core material, the firstopening being larger than a substrate pass through-hole; an electricallyinert material filling the first opening; and a second opening extendingparallel to the first opening through the electrically inert material,the second opening being at least as large as the substrate passthrough-hole and having sidewalls enclosed within the electrically inertmaterial.
 17. The device substrate of claim 16, wherein capacitor sheetis a laminate comprising at least a conductive layer and a dielectriclayer.
 18. The device substrate of claim 16, wherein the capacitor sheetcomprises two or more electrically isolated capacitor sheets, each ofthe two or more electrically isolated capacitor sheets being affixedadjacent to the surface of the core material.
 19. The device substrateof claim 16, wherein the electrically inert material is a resin.
 20. Thedevice substrate of claim 16, wherein the second openings are a passthough-holes.